Giải phương trình:
a) 3cos22x + 8sinx.cosx - 4
b) 2cos22x + (2 - \(\sqrt{2}\))cos2x - \(\sqrt{2}\) = 0
c) 2sin2x - (2 + \(\sqrt{3}\))cosx - 2 - \(\sqrt{3}\) = 0
d) -2cos4x - 2(1 - \(\sqrt{3}\))sin2x - \(\sqrt{3}\) + 2 = 0
f) 4cosx - 5sin\(\frac{x}{2}=1\)